They cover less but have more effective light. I read once that a fluorescent fixture without the side wings or shades loses 60% of the light for growing plants. The light spreads out when it should be directed dowmwards.

Your moving the lights around means that your plants will get different exposures to the light. It may work but it would not be something I would try. My opinion only

Many grower use light mover; but it may cause problems with the air duct slack. If the light is too close at top of the plant; then the duct may get dragged through plant, thus damaging them.